It may not look like a character from the Transformer franchise, but a tiny robot made in the US is able to change shape.

Built at the Massachusetts Institute of Technology (MIT), it uses magnets to mimic molecules that fold themselves into complex shapes.

The research could lead to robots that could be reconfigured to perform many different tasks.

But one expert said a lot of work was still needed.

Part-funded by the US Defense Advanced Research Projects Agency, the research was presented at the 2012 Intelligent Robots and Systems conference.

"It's effectively a one-dimensional robot that can be made in a continuous strip, without conventionally moving parts, and then folded into arbitrary shapes," said one of the researchers, Neil Gershenfeld, head of MIT's Center for Bits and Atoms.

To fold itself into a new shape, the device uses an "electro-permanent" motor - similar to the electromagnets used in scrapyards to lift cars.

It is composed of pairs of a powerful permanent magnet and a weaker magnet with a magnetic field that changes direction when an electric current is applied.

The magnetic fields of each magnet either add up or cancel each other, making the robot move.Research race

The prototype comes a year after the same team published a theory it was possible to create any 3D shape by folding a sufficiently long string of subunits.Still from Transformers: Dark Of The Moon Robots in the Transformer series easily change their shapes

Jeremy Pitt, deputy head of the Intelligent Systems and Networks Group at Imperial College London, said it would be challenging for such a robot to work alongside artificial-intelligence machines, but the technology could have many real-world applications.

"It is a fascinating example of what happens when mathematical proof, that an arbitrary 3D shape can be built from a sufficiently long string, meets engineering innovation - the miniaturisation of motors and magnets and the minimisation of power consumption," he said.

"There is going to be an interesting research race between groups trying to create reconfigurable structures out of such chains and those trying to build them out of independent self-assembling units."